High phosphorus content extreme pressure lubricant additive and method of preparation thereof



/ PREPARATION THEREQF United States Patent s 043 773 HIGH PHOSPHORUS cor-ITENT EXTREME PRES- SURE LUBRICANT ADDITIVE AND METHOD OF Warren W. Cortiss, William D. G'ilson, and Allan A. Manteulfel, Crystal Lake, 111., assignors to The Pure Oil Company, Chicago, IlL, a corporation of Ohio No Drawing. Filed Nov. 9, 1959, Ser. No. 851,561

20 Claims. (Cl. 252-46.7)

This invention relates to new and useful improvements in extreme-pressure lubricants and, more particularly, to a superior sulfurized-phosphorized lubricant additive which is substantially non-corrosive when used at elevated temperatures. This invention is further concerned with the preparation of sulfurized-phosphorized lubricant additives containing a high phosphorus content and to a method of preparing such additives.

Extreme-pressure lubricants and additives for production of extreme-pressure lubricants are well known in the lubricating art. When a lubricant is compressed between two moving metallic surfaces, high film strength is necessary to prevent the escape or squeezing out of said lubricant from between said surfaces, with consequent welding. The extreme pressures to which said lubricants are subjected when compressed between the contacting surfaces of a gear cause a rise in internal heat which is augmented by any friction generated by lack of point-lubricity. It has been found that lubricating oil fractions alone are unsatisfactory in that they do not have the required high lubricity and high film strength and consequently allow scoring and welding of gears on continued use. In the past, extreme-pressure additives have been used in conjunction with mineral lubricating oils to provide the desired lubricity and high film strength. F attyoils and fatty acid esters, which have been reacted with sulfur and/ or phosphorus sulfides, have been added to lubricating oils to improve the extreme-pressure characteristics thereof. In the past, it has been virtually impossible to prepare sulfurized-phosphorized lubricant additives which have a high phosphorus content and which have a low or controllable sulfur activity at service temperatures up to 300 F., or higher. Conventional, sulfurized-phosphorized, extreme-pressure additives have been prepared in the past by sulfurizing a fatty material to a relatively low sulfur activity (by heating to temperatures as high as 350 F.) and then reacting the sulfurized material with a sulfurand phosphorus-containing compound, such as a phosphorus sulfide (preferably P 8 or P 8 at temperatures of about 220 240 F. It has been impossible to process these sulfurized-phosphorized materials at temperatures sufiiciently high to render their sulfur activity (corrosivity) sufiiciently low for use at temperatures of 300 F. and higher. Sulfurized-phosphorized, extremepressure additives containing any substantial proportion of,

phosphorus compounds have been unusable at high temperatures due to the formation of insoluble polymeric lay-products which have made the product unsuitable for use.

It is therefore one objectof this invention to provide an improved extreme-pressure lubricant additive having a high phosphorus content and which is stable and noncorrosive when used at elevated temperatures. 1

' Another object of this invention is to provide an improved method for the preparation of a sulfurized-phosphon'zed, extreme-pressure lubricant additive which is p 3,043,173 Patented July 10, 1962 A feature of this invention is the provision of an improved process for the preparation of a phosphorized or phosphorized-sulfurized lubricant additive, which is thermally stable and non-corrosive at elevated temperatures, in which a fatty material or a sulfurized fatty material is phosphorized with a phosphorus sulfide in admixture with a nitrogen compound selected from the group consisting of C1842 fatty amines, C1642 fatty amides, C1842 fatty nitriles, and C1642 fatty amine salts.

A further feature of this invention is the provision of an improved extreme-pressure lubricant additive prepared by mixing a fatty material or a sulfurized fatty material with a C1642 fatty nitrogen compound selected from the group consisting of fatty amines, fatty amides, fatty nitriles, and fatty amine salts, and reacting said mixture with 05-15% wt. of a phosphorus sulfide at a temperature of 220350 F. for a time suificient to produce a non-corrosive product.

A further feature of this invention is the provision of an improved, non-corrosive, thermally, stable extremepressure lubricant consisting of a mineral lubricating oil containing an extreme-pressure additive prepared by phosphorization of a fatty material, or sulfurized fatty material, in admixture with a fatty amine, a fatty amide, a fatty nitrile, or a fatty amine salt.

Other objects and features of this invention will become apparent from time to time throughout the specification and claims as hereinafter related.

In general, our invention comprises a novel extremepressure lubricant additive and process of preparing the same. "In accordance with our process, a fatty material is treated with 05-15% Wt. of a phosphorus sulfide at a temperature in the range from about 220-350 F. in admixture with a fatty nitrogen compound selected from the group consisting of C1642 fatty amines, C1642 fatty amides, C1642 fatty nitriles, and C fatty amine salts. The fatty nitrogen compound is preferably mixed with the fatty material in an amount in the range from 0.5-5.0% wt. which is roughly proportional to the amount of phosphorus sulfide reacted therewith; This process is similarly applicable to the phosphorization of a fatty material which has been previously sulfurized. In such a case, the fatty material is mixed with about 5-10% Wt. sulfur and heated to a temperature of about 315375 F. for a time sufficient to convert the sulfur to a relatively inactive form. At the end of the sulfurization reaction, the product should cause a clean copper strip to turn light tan upon immersion therein for '1 minute at 300 F. inaccordance with ASTM test for sulfur activity. The sulfurized fatty material is then mixed with the fatty nitrogen compound and 0.5-

y 15% wt. of phosphorus sulfide, preferably phosphorus sesquisulfide, and heated at a temperature in the range substantially non-corrosive and thermally stable at elevated temperatures.

' Anotherobject of this invention is to provide an improved extreme-pressure lubricant composition which is substantially non-corrosive and thermally stable at elevated operating temperatures.

from about 220-350 for a time sufiicient to produce a substantially non-corrosive product. The product which is thus obtained, whether from a fatty starting material or a sulfurized fatty starting material, has a high phosphorus content which is not obtainable in the absence of the fatty nitrogen compound, and does not produce an insoluble precipitate upon heating, as occurs upon heating a sulfurized-phosphorized fatty material which has not been mixed with the fatty nitrogen compound prior to the phosphorization reaction. The product which is obtained has a very low sulfuractivity and is non-corrosive toward gears at temperatures up to about350 F. This extremepressure additive, which is produced in accordance with this inventiomis soluble in all types of petroleum lubricating oils and enhances the extreme-pressure properties of such oils to make them useful under conditions of high pressure and temperature; p v

1 'In carrying out this invention, the starting material for preparation of the extreme-pressureadditive is a-fatty material. The term fatty materialincludes solid and liquidfats and fatty oils of all kinds, and is particularly directed to naturally occurring and synthetic esters of fatty acids in which the fatty acid radical is unsaturated and "contains at the most two unsaturated carbon-to-carbon bonds. The fatty esters which are contemplated include the fatty acid esters of alcohols, glycols, glycerols, and other monoand polyhydroxy organic compounds. Naturally-occurring fatty materials which are useful in this invention include animal fats and fatty oils, such as tallow, lard oil, spermoil; degras, vegetable fats and oils, such as cotton-seed oil, soybean oil, coconut oil, etc. Synthetic fatty materials which may be used include synthetic esters of fatty acids, such as methyl esters of lard oil, lower alkyl esters of tall oil, and synthetic esters of glycols and other polyols, such as propylene glycol dioleate, and pentaerythritol tetraoleate.

The fatty nitrogen compounds which may be used in this invention include C1642 fatty amines, amides, nitriles and amine salts. These fatty nitrogen compounds may be used in the formof separatepure compounds or as mixtures which are derived from naturally occurring mixtures of fatty acids or the like. Preferred fatty nitrogen compounds 'include Duomeen T, which is a substituted trimethylene diamine of theformula RI T-CHzOHgCH NH where the R group is a mixture of aliphatic radicals derived from tallow acids and consists essentially of a mixture of C normal alkyl radicals and a C normal alkenyl radical. The dioleate of Duomeen T is likewise a preferred nitrogen compound for use in this invention. Fatty. amines which maybe used include C amines, such as octadecylamine, hexadecylamine, coco amine, etc.

, These amines include any primary or secondary amine which is derived from the saturated or unsaturated aliphatic radicals which are found in naturally occurring fats. Armeen I-ITD (manufactured by Armour 8: C0.) consists of a mixture of about 25% hexadecylamine, 70% octadecylamine, and octadecenylamine, and is useful in this invention. Salts of the C fatty amines which may be used in this invention include the fatty acid salts, such as the acetate, propionate, butyrate, etc., as well as the higher fatty acids including the stearate, palmitate, oleate, etc. In general, any C fatty acid, whether saturated or unsatrated, and any derivative thereof containing a non-reactive substituent, may be used for forming salts .of a fatty amine which may be used in this invention. The fatty amides and fatty nitriles which are useful in this invention includes stearylamide, stearonitrile,

, palmitylamide, palmitylnitrile, olelyl amide, oleonitrile,

behenyl amide, gadoleyl amine, cetoleyl amide, erucyl amide, eleostearylamide, and thecorresponding nitriles thereof.

The phosphorus. sulfides which may be used in this invention include all of the binary compounds of phosphorus and sulfur, preferably, phosphorus sesquisulfide or phosphorus pentasulfide. e

The following non-limiting examples are illustrative of the scope of this invention:

EXAMPLE 1 A conventional, Sulfurizedphosphorizedextreme-pressure base was prepared by reacting 55 sperm oil with 7.5% wt. sulfur at 310-320 F.,for 7 hours until the A sulfurized product reached a tan copper strip end-point (as measured by immersion of a clean copper strip in the material at 300 F.'f01' 1 minute). material was then reacted with 0.8% wt. of phosphorus sesquisulfide (P 8 at 220-230 F. for 1 hour, which The sulfurized produce an extreme-pressure lubricant composition which is useful as a gear oil under extreme-pressure conditions. This extreme-pressure additive, however, is extremely corrosive (has high sulfur activity) at temperatures in excess of about 250 F. An attempt was made to lower the corrosiveness of the product at elevated temperatures by heating it at elevated temperatures approaching 300 F. to cause the sulfur to be more tightly bound in the fatty oil and thus render the product non-corrosive at elevated temperatures. As the product was heated toward 300 E, which was the anticipated temperature of use of the product, an insoluble material formed and precipitated which rendered the material unsatisfactory as an extreme-pressure additive.

EXAMPLE II In another experiment,.55 sperm oil was mixed with 7.5% sulfur and heated to 345 -355 F. for 7.5 hours. At the end of this reaction time, the product had reached a tan copper strip end-point. The sulfurized sperm oil was then mixed with 2% wt. of Duomeen T dioleate (N- tallow trirnethylene diamine dioleate) and reacted with 0.8% wt. of phosphorus sesquisulfide. The phosphorization reaction was carried out for 1 hour at 275 F. and the product heated for 1 hour at 300 F. and for 3 hours at 325 F. The product which was obtained was oilsoluble and had low sulfur activity at 300 F. (exhibited substantially no corrosivity toward gear metals). N0 precipitate formed during the reaction or during the additional heating steps, and the product which was obtained was thermally stable and suitable for extended use at temperatures up to about 350 F. without exhibiting an appreciable sulfur activity.

EXAMPLE III variations in the amount of phosphorus sesquisulfide that;

can be incorporated in a fatty oil using the method of this invention. In one experiment, sulfurized sperm oil,

containing 7.5% wt. sulfur, was reacted with 5% wt. phosphorus sesquisulfrde in admixture with 1% wt. of

Duomeen T dioleate at 260 F. to yield an oil-soluble product which functioned satisfactorily as an extremepressure lubricant base. In another experiment, sulfurized sperm oil, containing 7.5% wt. of sulfur, was mixed with 3% !wt. of Duomeen T dioleate and reacted at 260 F.

w-ithl0% wt. of phosphorus sesquisulfide. The amount of phosphorus sesquisulfide which can be reacted with a sulfurized fatty oil in accordance with this invention is approximately proportional to the amount of the amine salt which is present. The proportion is not exact and the range of the proportion has not been accurately determined. However, it requires substantially more of the amine salt in'phosphorizing a fatty oil with 10% phos-- phorus sesquisulfide than is required in phosphorizing the same oil with only 5% phosphorus sesquisulfide. When a sulfurized fatty material is phosphorized with 5% phosphorus sesquisulfide, it is preferred that 2-3% of amine salt be used.

EXAMPLE IV In another series of experiments, it was demonstrated that the use offatty nitrogen compounds, such as amine.

salts (e.g., Duomeen T dioleate), are useful in the phosphorization of fatty oils which have not been previously reacted with sulfur, and that the amount of phosphOrus which can be incorporated in the fatty oil is related to .the amount of the amine salt which isrused. A series of experiments were carried out in which 55- sperm oil was heated with 5% wt..of phosphorus sesquisulfide for 4 hours at 260 F., first with no amine salt present and subsequently with increasing amounts of the amine salts in the range from 1-5% wt. In each experiment, the

heating to temperatures of the order of 250".- 350 F.

EXAMPLE VI In still another experiment, methyl esters of lard oil were reacted with 5% of phosphorus sesquisulfide in the presence of 2% wt. Duomeen T dioleate at 220240 F. for 4 hours.. The resulting product was uniform and clear and was soluble in'aromatic oils to produce an extreme-pressure lubricating oil. When the same experiment was carried out, omitting the Duomeen T dioleate, the product was unsatisfactory due to formation of insoluble material after a very short vreaction time.

EXAMPLE" v11 for periods of time adequate to reduce the sulfur activity.

tothe lever at which the product caused only atrace of red tarnish in a three-minute copper strip test 'at220 230 F. In each case, the product was allowed tostand for 24 hours and observed for formation of insoluble product which was obtained was allowed to stand for precipitate. Results of these experiments are set forth 24 hours and the amount of precipitate was measured. in Table II. c The results are set forth in Table I and indicate that at Table II a 5% wt. concentration of phosphorus sesquisulfide, a 5 V 225% concentration Duomeen T diolcate gives Percent Percent Temp. Time Product After Solubility of optimum results. ms. DTD c F.) (Hrs) 24 Hours Producg t Table I m n 1 1 260 4 hrs., 55 Clear Soluble. Experiment N0... 1 2 3 4 5 6 7 8 10 min.

1. None 260 4 hrs., 55 Light Not Tested.

min. Polymer Percent Duomeen 5 2 260 4 hrs., 55 lear Soluble.

'IDioleate 0 1.00 2.00 2. 25 2.50 3.00 4. 00 5.00 mil Percent Precipi- 10 2 260 6hrs'. do Sl. Soluble.

tate after 25 hrs. 0.50 0.25 0.15 0.09 0.10 0.10 0.60 2.00 10 N 2 0 61 Heavy N t T t d,

' Polymer.

15 2 260 0% hrs do Do. From these experiments and another series of experiments, 15 5 260 3 hrs, 15 Clear oluble. in which the amount of Duomeen T dioleate was varied, using a sulfu-rized fatty starting material, it was found that x the use of excessive amounts of the amine salt caused DuomeenTdloleate the formation of an insoluble foam in some instances. EXAMPLE VIII Consequently, we prefer that no more than the minimum Three extremeqaressure additives were prepared fo eifcctive amount of the amine salt or amine or other fatty comparative evaluation and were used in the prepara q s Q PP be used in the Process 9 this mven' tion of extreme-pressure lubricants. Additive A was tlon- This mlmmum efiecuve amount vanes somewhat prepared in accordance with Example III and was phosfor different amine salts and amines and other fatty mtrophorized using 5% phosphorus sesquisulfide and 215% g compounds, but is generally in F range of 1 Duomeen T dioleate. Additive B? was also prepared wt. of the fatty material or sulfunzed fatty material for in accordance with Example In using 10% phosphorus reaction with 05-15% of Phosphorus Sesqmsulfide- :sesquisulfide and 4.5% Duomeen T dioleate. Additive EXAMPLE V C was made in accordance with l-Ixample I, which d t hi h the corresponds to the procedure described in Chapman et al., Addmonal.e.)penments 9 came on w 0 2,910,438. Lubricant compositions were prepared by disorder of addmon of the amme l was vaned' In solving portions of the extreme-pressure additives in a experiment, the product was sulfurlzed and phosphonzed 170 viscosity neutral OiL These compositions were as Example I and amme Salt added subseqllenfly evaluated in the Falex maximum load-torque test, the durmg the final, heatmg amber .eipelflment Shell four-ball weld-point test, and the Shell four-ball the.product was prepared. 9 ImXmg a fatty m1 Wlth the wear-diameter test (20 kg. load for 5 minutes). In amme Salt and .phosghonzmgr the Same by an Table III, the results of each of the aforementioned tests attempted .reactlon with 325-375 In the are set forth with respect to the lubricating compositions first expenment Whel} the amine Salt was added. after produced by incorporating the various additives at difthe phosphosulfurization reactlon, the product did not 4.0 ferent concentrations in the oil 1 form a precipitate upon heating to an elevated temperature, but did not decrease materially in sulfur activity Table III upon heating. In the second experiment, the attempt at sul'furization of the phosphorized fatty oil produced a Falex Test Shell Four-BallTest very heavy sludge which precipitated from the product. 5 Additive It therefore appears that it is necessary that the amine percent Maximum Torque Weld Wear salt or other fatty nitrogen compound be added to the Q Dlametel fatty material prior to reaction with the phosphorus sulfide if he advantages of the invention are to be realized g 2 8g 32% 8-333 and a product is to be obtained which has low sulfur 5 3: 250 88 210 0'. 270 activityand which does not produce a precipitate upon 1% 3: 3% 5:8 8:232

The Falex and Shell four-ball tests are well known in the art and a description of the manner of carrying out such tests is not considered essential to a description of the invention. A description of these tests may be found in Manteuifel et al.-, 2,830,952, and Bowden'et aL, 2,830;v

thus apparent that the extreme-pressure additives'of thisinvention are not only superior in terms of low sulfur activity and thermal stability but also provide superior extreme-pressure and wear-resistant properties at low concentrations inalubricatingoil. Y

EXAMPLE IX In another experiment, lard oil was mixed with 2 Wt. of Armeen HT and reacted with 5% wt. of phosphorus sesquisulfide at 250 F. for a period of 4 hours. Armeen.

, the experiment did not produce a precipitate upon heating to 300 F. and was not corrosive at elevated temperatures. A copper strip immersed in this product at 240 F. for 1 minute acquired only a slight tarnish. The product was of a uniform yellow-brown color and was quite clear.v

This product was dissolved at a 1.0% concentration in 100 VI, 85 SUS at 100 F., neutral oil and produced a clear, stable solution from which there was no separation after a period of 3 weeks. The product produced by dissolving the phosphorized lard oil in the neutral oil is an extreme-pressure lubricant which is useful in the lubrication of gears.

In a series of experiments, thQC16 1g primary amine was replaced by other amines to determine the scope of the invention. In these experiments, attempts were made to carry out the phosphorization reaction in the presence of ethylenedia'mine,v aniline, butylamine, and a C nitrile. In each case, the product obtained was unsatisfactory due to separation of a precipitate either from the product or upon dissolving the product in a lubricating oil. Also, the products obtained in this manner were not thermally stable and were considerably more corrosive thanthe product obtained following this invention.

7 EXAMPLE X When lard oil is sulfurized by heating with 7.5% sulfur at 325 F. for 7 /2 hours and subsequently phosphorized in accordance'with this invention, a non-corrosive, thermally stable product is'obtained. When the sulfurized lard oil is mixed with 2% Armeen HT and phosphorized with of phosphorus sesquisulfide, there is obtained a product which is soluble at concentrations of up to about 10% in a 100 VI, 85 SUS-at 100 F., neutral oil to produce a lubricant having excellent extreme-pressure properties. I

When fatty nitriles and fatty amides are substituted for the fatty amine or fatty amine salt in the phosphorization reaction, it is usually necessary to react the sulfurized fatty .oil with the phosphorus sesquisulfide for a slightly longer time to obtain a more completely phosphorizedsulfurized product. The products which are obtained in such cases, however, are soluble in lubricating oils and produce excellent extreme-pressure lubricants which are thermally stable and not corrosive at elevated tempera tures. It should be noted that while the examples which have been given of lubricating oil compositions containing the products of this invention had been directed primarily to neutral oils, these extreme-pressure additives are soluble phorized'extreme-pressure additives are least soluble.

EXAMPLE XI When degras is reacted with phosphorus sesquisulfide, at;temperatures up to about 240 F., a precipitate forms. If degras ismixed with 2% Duomeen T dioleate and re acted with 5 phosphorus sesquisulfide at 240 F., a clear liquid 'product is obtained which contains no precipitate and which is very soluble in lubricating oils. 84.4% of degras, which has been reacted with 5% phosphorus sesquisulfide in admixture'with 2% Duomeen T dioleate at 240 F, is reacted with 15.6% .of barium hydroxide,-there is obtained a metal salt of the phosphosulfurized fatty material which is soluble in lubricating oils and has both deter-gent and extreme-pressure properties. A 100 VI neutral oil containing 240%, of the barium salt of phospho-sulfun'zed degras, prepared as above described, is a satisfactory lubricant for use in When,

automotive engines. This process is similarly applicable to the preparation of metal salts of phosphorized-sulfurized fatty materials by reaction of metallic oxide, hydroxide, or carbonate with a phospho-su'lfurized fatty material produced in accordance with this invention. For example, when the product of Examples II to VIII is reacted with any alkali or alkaline earth metal oxide, hydroxide, or carbonate (e.g., Li O, Na- O, K 0, BaO, MgO, SrO, Ba(OH) NaOH, K CO BaCO etc.), there is produced an oil-soluble salt of the phosphorized-sulfurized material, which combines extreme-pressure properties and detergent propertie for use in motor oils.

While we have described this invention fully and completely with special emphasis upon several preferred embodiments, we wish it to be understood that within the scope of the appended claims this invention may be practiced otherwise than as specifically described.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of preparing a thermally stable, noncorrosive extreme-pressure lubricant additive which comprises mixing a material selected from the group consisting of fatty material and sulfurized fatty material with 0.5-5 .0% wt. of a fatty nitrogen compound selected from the group consisting of C1642 fatty amines, C1642 fatty amides, C fatty nitriles, and C fatty amine salts, and reacting said mixture with 05-15% wt. of a phosphorus sulfide at a temperature in the range from about 220-350 F. for a time sufficient to produce a noncorrosive product, asv measured by the copper-strip corrosion test.

2. A method in accordance with claim 1 in which the fatty material is lard oil.

3. A method in accordance with claim 1 in which the amine of the formula RNHCH CH CH NH where R is a mixture of aliphaticradicals derived from tallow.

6. A method in accordance with claim 1 in which the nitrogen compound is the dioleate of a fatty diamine of the formula RNHCH CH CH NH where R is a mixture of aliphatic radicals derived from tallow.

7. A method in accordance with claim 1 in which the phosphorus sulfide is phosphorus sesquisulfide.

8. :A. method in accordance with claim 1 in which the sulfurized fatty material is prepared by heating fatty material with 5-10% wt. of sulfur at 3l5-375 F. until a tan copper strip, as measured by 1-minute immersion at 300 F., end-point is obtained.

9. A method in accordance with claim 1 in which the phosphorized-sulfurized product is reacted with a compound of the group consisting of alkali and alkaline earth metal oxides, hydroxides, and carbonates to produce, an oil-soluble compound of the metal. 7

10. A method of preparing a thermally stable, noncorrosive extreme-pressure lubricant additive which comprises heating lard oil with 5-10% wt. sulfur at 315 375 F. until a tan copper strip, as measured by 1-minute immersion in 300 F., end-point is obtained, mixing the sulfurized lard oil with about 23% of N-tallow trimethylene diamine dioleate and about 5% of phosphorus sesquisulfide and heating the mixture at about 260 F. for about 4 hours until a non-corrosive product is obtained, as measured bythe copper-strip corrosion test.

11. A method of preparing a thermally stable, noncorrosive extreme-pressure lubricant additive which com- 1-minute immersion in 300 F., end-point is obtained,

mixing the sulfurized sperm oil with about 23% of N- tallow trimethylene diamine dioleate and about 5% phosphorus sesquisulfide and heating the mixture at about 260 F. for about 4 hours until a non-corrosive product is obtained, as measured by the copper-strip corrosion test.

12. An extreme-pressure lubricant additive produced in accordance with claim 1.

13. An extreme-pressure lubricant additive produced in accordance with claim 2.

14. An extreme-pressure lubricant additive produced in accordance with claim 3.

15. An extreme-pressure lubricant additive produced in accordance with claim 4.

16. An extreme-pressure lubricant additive produced in accordance with claim 6.

17. An extreme-pressure lubricant additive produced in accordance with claim 9.

18. A mineral lubricating oil containing a minor amount of an extreme-pressure additive prepared in accordance with claim 1 in an amount suflicient to enhance the load-carrying and wear-resisting properties of the oil.

19. A mineral lubricating oil containing a minor amount of an extreme-pressure additive prepared in accordance With claim 6 in an amount suflicient to enhance the load-carrying and wear-resisting properties of the oil.

20. A mineral lubricating oil containing a minor amount of an extreme-pressure additive prepared in accordance with claim 9 in an amount sufficient to enhance the load-carrying and wear-resisting properties of the oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,242,260 Prutton May 20, 1941 2,403,474 Bartieson et al July 9, 1946 2,506,572 Bartleson May 9, 1950 2,614,075 Bartleson Oct. 14, 1952 2,809,935 Chapman etal. Oct. 15, 1957 2,820,013 Chapman et a1. Jan. 14, 1958 2,910,438 Chapman et a1. Oct. 27, 1959 

1. A METHOD OF PREPARING A THERMALLY STABLE, NONCORROSIVE EXTREME-PRESSURE LUBRICANT ADDITIVE WHICH COMPRISES MIXING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF FATTY MATERIAL AND SULFURIZED FATTY MATERIAL WITH 0.5-5.0% WT. OF A FATTY NITROGEN COMPOUND SELECTED FROM THE GROUP CONSISTING OF C16-22 FATTY AMINES, C16-22 FATTY AMIDES, C16-22 FATTY NITRILES, AND C16-22 FATTY AMINE SALTS, AND REACTING SAID MIXTURE WITH 0.5-15% WT. OF A PHOSPHORUS SULFIDE AT A TEMPERATURE IN THE RANGE FROM ABOUT 220*-350* F. FOR A TIME SUFFICIENT TO PRODUCE A NONCORROSIVE PRODUCT, AS MEASURED BY THE COPPER-STRIP CORROSION TEST. 